Interplay of Metallophilic Interactions, π–π Stacking, and Ligand Substituent Effects in the Structures and Luminescence Properties of Neutral PtII and PdII Aryl Isocyanide Complexes

Packing interactions in the crystal structures of a series of cis-M(CNAr)2Cl2 complexes (M = Pt, Pd; Ar = substituted phenyl) were examined and correlated with the luminescence properties of the Pt complexes. The structures of the PhNC and p-tolyl isocyanide complexes exhibit extended chains of metallophilic interactions with M···M distances of 3.24–3.25 and 3.34 A, respectively, with nearly isostructural Pt and Pd compounds. Both structure types contain void channels running parallel to the M···M chains. The channels are 3–4 A wide and vacant for the phenyl structures, while those in the p-tolyl structures are up to 7.6 A wide and contain water. These channeled structures are stabilized by a combination of metallophilic bonding and aryl π–π stacking interactions. The Pt structure with 4-F substituents also features extended Pt···Pt chains, but with longer 3.79 A distances alternating with shorter 3.37 A contacts. Structures with 4-CF3 and 4-OMe substituents exhibit mostly isolated dimers of M···M contact...